Many existing telephone systems utilize a centralized call manager for controlling phones directly connected to the call manager, as well as for controlling telephones located at remote branches. Using centralized control is beneficial because control software only needs to be implemented in one location and experienced personnel are not required at each of the various branches to maintain associated call manager software. Such a centralized call manager may also be utilized to manage a call center in which a plurality of incoming calls are received by agents. One example of utilization of a call center is for airline reservations. The management of the call center may involve determining which phone in any branch receives a particular phone call. It is important to maintain the capability of a call center even at times where certain portions of the call center network are disabled.